<!DOCTYPE html >
<html id="aUMmWumun1aCB3_v.YdpA371uedi-17289661" data-origid="17289661" class="anndoc" data-anndoc-version="2.0" lang="" xml:lang="" xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <meta charset="UTF-8"/>
    <meta name="generator" content="net.tagtog.anndoc.v2.parsers.bio.PubMedAbstractsParser_v0_1$"/>
    <meta name="dcterms.source" content="http://www.ncbi.nlm.nih.gov/pubmed/17289661"/>
    <title>aUMmWumun1aCB3_v.YdpA371uedi-17289661</title>
  </head>
  <body>
    <article>
      <section data-type="title">
        <h2 id="s1h1">Molecular composition of IMP1 ribonucleoprotein granules.</h2>
      </section>
      <section data-type="abstract">
        <h2 id="s2h1">Abstract</h2>
        <div class="content">
          <p id="s2p1">Localized mRNAs are transported to sites of local protein synthesis in large ribonucleoprotein (RNP) granules, but their molecular composition is incompletely understood. Insulin-like growth factor II mRNA-binding protein (IMP) zip code-binding proteins participate in mRNA localization, and in motile cells IMP-containing granules are dispersed around the nucleus and in cellular protrusions. We isolated the IMP1-containing RNP granules and found that they represent a unique RNP entity distinct from neuronal hStaufen and/or fragile X mental retardation protein granules, processing bodies, and stress granules. Granules were 100-300 nm in diameter and consisted of IMPs, 40 S ribosomal subunits, shuttling heterologous nuclear RNPs, poly(A)-binding proteins, and mRNAs. Moreover granules contained CBP80 and factors belonging to the exon junction complex and lacked eIF4E, eIF4G, and 60 S ribosomal subunits, indicating that embodied mRNAs are not translated. Granules embodied mRNAs corresponding to about 3% of the human embryonic kidney 293 mRNA transcriptome. Messenger RNAs encoding proteins participating in the secretory pathway and endoplasmic reticulum-associated quality control, as well as ubiquitin-dependent metabolism, were enriched in the granules, reinforcing the concept of RNP granules as post-transcriptional operons.</p>
        </div>
      </section>
    </article>
  </body>
</html>
